Thailand Rental Electricity Overcharge Index: Province-by-Province, Updated Every Quarter

Quarterly Trend

This table accumulates one row per quarter (each wave is an independent market-snapshot sample, not a panel of the same properties). When two quarters' confidence intervals overlap, the change is reported as not statistically significant.

The trend sparkline appears once at least 2 quarters of data exist — next wave Oct 2026.

Province Comparison Table

Only provinces with at least 5 advertised-rate listings in the latest quarter are listed individually (11 provinces); the remaining 35 provinces are combined into one row to avoid false precision. Click a column header to sort.

⚠ = fewer than 10 advertised-rate listings — interpret with caution (wide confidence interval).

Bangkok vs Other Provinces

Rental Water Charges 2026: 400 Listings Surveyed, Median 18 THB/Unit — Provinces Cost More Than Bangkok

The same dataset behind the electricity index (400-listing sample, Jul 2026) also captured water charges — the first nationwide dorm/rental water-price statistics published with raw data. Unlike electricity, official water tariffs are tiered ladders that differ by area (MWA vs PWA), so we report the distribution of advertised prices and provide the official ladders as context — no single-threshold judgment.

The mean is pulled up by a few extreme values (max 100 THB/unit) — the median is the headline figure to cite.

Bangkok vs Provinces: Water Flips the Electricity Pattern

Rental electricity barely differs nationwide, but advertised water prices are clearly higher outside Bangkok — and half the explanation sits in the official tariff structure itself (see the mechanisms below).

Why Provincial Water Costs More Than Bangkok — 3 Mechanisms in the Official Tariff

1. 1

   A ~20% higher starting rate: the PWA residential ladder starts at 10.20 THB/m³ vs MWA's 8.50, and PWA's 11–20 m³ tier is 16.00 THB/m³ — roughly 1.9× MWA's rate over the same range.

2. 2

   The 50 m³ cross-class rule: under the PWA notification, a Type-1 (residential) customer who uses more than 50 m³ in a month is charged at Type-2 (government & small-business) rates counting from the 51st m³ onward — the first 50 m³ stay on the Type-1 ladder; the whole month is not reclassified. A whole dorm building on one master meter exceeds this threshold in virtually every case, raising the landlord's per-unit cost across everything above it.

3. 3

   Dense dorm zones sit in higher-rate areas: many provincial university/dorm belts (e.g. Pathum Thani–Rangsit, Chonburi–Sriracha) fall in PWA's private-joint-venture concession zones, which use a pricier rate table than standard nationwide PWA rates.

How Thai Rentals Charge for Water (All 400 Sampled Listings)

Flat per-person (44 listings): median 100 THB/person/month (P25–P75: 100–200) — Bangkok's median of 150 THB/person (n=11) tops the provinces' 100 (n=33). Flat monthly charges have a median of 200 THB/month.

Official Waterworks Rates (Context, Not a Judgment Line)

Official rates are volume-tiered ladders that differ by provider — they cannot be compared 1:1 with a dorm's per-unit price, because building owners buy water through a master meter that climbs higher tiers than a normal household. The monthly meter service fee climbs with meter size too: a household's Ø 1/2" meter costs MWA 25 THB / PWA 30 THB, but a building's master meter is usually larger — at Ø 2" it is MWA 300 THB / PWA 350 THB per month. PWA calls this line item “ค่าบริการทั่วไป” (general service charge). All figures ex-VAT.

Key PWA rule: a Type-1 (residential) customer who uses more than 50 m³ in a month is charged at Type-2 rates counting from the 51st m³ onward (the first 50 m³ stay on the Type-1 ladder) · MWA's volumetric rates have applied since Dec 1999 and its monthly meter service fee since November 2006; PWA's volumetric figures are the currently published notification (that rate page states no effective date), while PWA's general service charge comes from clause 11 (ข้อ ๑๑) of the PWA Regulation B.E. 2540, as amended · Verify at the source: MWA rate and service-fee tables · PWA rate table · PWA general service charge (customer guide, §9).

Limitations of the Water Data

1. 1

   PWA effective dates are only partly documented: PWA's volumetric rate page states no effective year, so the ladder figures here are cited only as 'current rates per the PWA notification' — we do not assert which year's notification they belong to. The general service charge (30 THB/month on a Ø 1/2" meter) does have a specific instrument behind it: clause 11 of the PWA Regulation B.E. 2540, amended by Amendment No. 3 dated 4 July B.E. 2543. That is the date the amendment was signed, not a commencement date — we did not obtain its commencement clause.

2. 2

   The >50 m³ blended cost (20.99–25.09 THB/m³) is our own arithmetic, not a figure the waterworks authorities publish. The method: apply the official cross-class rule to a master meter using 300 m³/month — the first 50 m³ at Type-1 rates, everything from the 51st m³ at Type-2 rates — with the low end taken from PWA's nationwide rate table and the high end from its private-joint-venture table (Phuket / Ko Samui / Ko Phangan use a separate, higher table and are not covered by this range). Volumetric charges only: the monthly meter service fee and VAT are excluded.

3. 3

   Dorm customer-class boundaries have grey areas: PWA criteria place dorms/flats/apartments in the residential class, but a 'business accommodation' class may overlap in some cases — per-property classification is decided by the local waterworks branch, and this page does not adjudicate any specific property's class.

How the Index Is Calculated

Limitations

A condensed version of the full report's six declared limitations — read them all on the survey page.

1. 1

   The index covers only listings that advertise a rate (~63.5% of the sample) — 'call to ask' listings may price differently.

2. 2

   Advertised rates can differ from what contracts actually charge — the index measures advertised prices, not real bills.

3. 3

   Small-sample provinces (⚠ rows) have wide confidence intervals — their percentages can swing next quarter without the market actually changing.

4. 4

   Each quarter is an independent market snapshot (not a panel) — small quarter-to-quarter moves may be sampling noise; overlapping confidence intervals are reported as not significant.

Download the Data

Open data under CC BY 4.0 — free for media and research reuse; cite 'CapSolar Overcharge Index' with a link back to this page.

• Quarterly index series (cumulative CSV)CSV
• Province table (cumulative CSV)CSV
• Baseline wave aggregates, Jul 2026 (survey report CSV)CSV
• Raw water data, 400 rows, Jul 2026 (per-listing CSV, province level)CSV

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